Messages in this thread | | | Subject | Re: Quick review of -rt RCU-related patches | From | Peter Zijlstra <> | Date | Wed, 05 Oct 2011 00:12:35 +0200 |
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On Wed, 2011-10-05 at 00:05 +0200, Thomas Gleixner wrote: > > peter_zijlstra-frob-rcu.patch > > > > Looks OK. Hmmm... Should this one go to mainline? > > Oh, looks equivalent, actually. So why the change? > > Peter ?
- if (in_irq() || in_serving_softirq()) { + if (preempt_count() & (HARDIRQ_MASK | SOFTIRQ_OFFSET)) {
For !rt its equivalent yes, for rt otoh its not:
int in_serving_softirq(void) { int res;
preempt_disable(); res = __get_cpu_var(local_softirq_runner) == current; preempt_enable(); return res; }
However invoke_softirq() will still add SOFTIRQ_OFFSET so we need to look at that to avoid recursion issues.
The changelog describes this. So this change is a direct consequence of -rt frobbing the softirq stuff and thus isn't needed upstream.
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